Wednesday, July 27, 2011

A Tale of 2 Mail Servers Threading

This little server is an old Dell rack server, about 4 years old maybe and runs Windows Server 2003 and is up to date on all patches and fixes for the NOS and the Mail application.

The other is brand new (under a year) and runs Windows Server 2008, because it had to, and is supposed to be up to date as well.

The Old server is a happy go lucky type of server, runs mail, instant messaging and push email/mobile solutions in addition to a handful of applications for 6 domains.

The New server is also happy but not so lucky and ONLY runs mail for 2 domains.

The Old server is the primary work horse, all mail comes into it from the SPAM appliance, internal and external mail as well. Attachment sizes are reasonable(25MB) for sending and unlimited for incoming. We encourage good email habits this way.

The New server has no limits on sending or receiving. Here lies the problem.

If the New server needs to send an attachment that is 50MB, the server will refuse to accept any emails from the Old server while it waits for it's threading to clear from sending this monster file. This is bad. Very bad.

We do not manage the New server yet perpetually must explain how SMTP works, why security like TLS is important and why size matters for attachments.

I had no idea Exchange was single threaded, thought for sure by now it was mutli threaded, especially that beast of a 64bit server, but evidently not the way these guys built it.

Anyone have some insight on this I will be more than happy to point the New server team to how to resolve this.

In the interim Domino is perfectly happy to keep holding their mail in queue and DDM is sending us notifications about the issue, as it should be, so we are monitoring their servers in addition to ours. Should start charging them for it.